Enantioselective N‐Heterocyclic Carbene Catalyzed Bis(enoate) Rauhut–Currier Reaction

N-Heterocyclic carbenes (NHCs) containing triazolium motifs have emerged as a powerful tool in organocatalysis. Recently, various NHC pre-catalyst mediated organic transformations have been developed successfully. This article aims to compile the current state of knowledge on NHC-triazolium catalysed enantioselective name reactions and introduce newly developed catalytic methods. Furthermore, this review article framework provides an excellent opportunity to highlight some of the unique applications of these catalytic procedures in the natural product synthesis of biologically active compounds, notably the wide range of preparation of substituted chiral alcohols, and their derivatives. This article provides an overview of chiral NHC triazolium-catalyst libraries synthesis and their catalytic application in enantioselective reactions.

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“…The reaction provides moderate to good yield with selectivity up to 96% ee (Scheme 54). 133 Template for SYNTHESIS Thieme…”

Section: Enantioselective Rauhut-currier Reactionmentioning

confidence: 99%

Recent Advances in Enantioselective Organocatalytic Reactions Enabled by N-Heterocyclic Carbenes (NHCs) Containing Triazolium Motifs

Sharma¹,

Chatterjee

Dhayalan

et al. 2022

Synthesis

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“…The direct application of NHC as the sole catalyst was presented by Anand in 2018 (Scheme 26), but this reaction was not efficient without the use of LiCl, which stabilizes the produced enolate [188]. In 2019, Lupton and co-workers exploited the high nucleophilicity of N-heterocyclic carbenes to achieve intramolecular RC reaction of bis(enoate) substrates (Scheme 27) [189]. The addition of NHC resulted in the formation of an enolate, which then cyclized to form the lactone, with a new C-C bond between the α-position of one activated alkene and the β-position of the second alkene.…”

Section: Rauhut-currier Reactionmentioning

confidence: 99%

“…In this case, imines are strongly electrophilic; therefore, initially, carbene reacts with ketene to generate a zwitterionic azolium enolate. It reacts further with the imine and forms the final product after In 2019, Lupton and co-workers exploited the high nucleophilicity of N-heterocyclic carbenes to achieve intramolecular RC reaction of bis(enoate) substrates (Scheme 27) [189]. The addition of NHC resulted in the formation of an enolate, which then cyclized to form the lactone, with a new C-C bond between the α-position of one activated alkene and the β-position of the second alkene.…”

Section: Staudinger Cycloadditionmentioning

confidence: 99%

Organocatalytic Name Reactions Enabled by NHCs

et al. 2020

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Giving reactions the names of their discoverers is an extraordinary tradition of organic chemistry. Nowadays, this phenomenon is much rarer, although already named historical reactions are still often developed. This is also true in the case of a broad branch of N‑heterocyclic carbenes catalysis. NHCs allow many unique synthetic paths, including commonly known name reactions. This article aims to gather this extensive knowledge and compare historical reactions with current developed processes. Furthermore, this review is a great opportunity to highlight some of the unique applications of these procedures in the total synthesis of biologically active compounds. Hence, this concise article may also be a source of knowledge for scientists just starting their adventure with N‑heterocyclic carbene chemistry.

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“…While these conditions would ultimately serve in our subsequent studies, further optimization was attempted. [15] Heterocycles were introduced, with 2-furyl hydrocoumarin 10 h being formed in 69 %y ield and 90:10 er. Catalyst B4 (N-t-Bu) gave 10 a in 49 % yield although with very low enantioselectivity ( Theg enerality of the reaction was examined through modification of the Rgroup,EWG group,and aromatic linker ( Table 2).…”

mentioning

confidence: 99%

“…X-ray crystallographic analysis was performed with 10 d to determine the absolute configuration. [15] Heterocycles were introduced, with 2-furyl hydrocoumarin 10 h being formed in 69 %y ield and 90:10 er. Introduction of an alkyl group was tolerated, with cyclohexyl 10 i and crotonate derivative 10 j being prepared in 44 %a nd 67 %y ield and with high enantioselectivity (95:5 and 93:7 er).…”

mentioning

confidence: 99%